• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1769-1771
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• 2000

The structural, electrical and gas sensing properties of $LaFeO_3$ thick films with different heat treatments were examined. As the heat treatment temperature increases, the intensity of dominant(121) phase increases in XRD measurements. Activation energy changes with the heat treatment and sensitivity is high for the samples with high activation energy, $LaFeO_3$ films showed high sensitivity to NO, $NH_3$ and $C_{4}H_{10}$ gases.

• 공학교육연구
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• 제22권4호
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• pp.43-49
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• 2019

A case of course-embedded assesment in electronic engineering was studied. In particular, a realistic evaluation system was developed in consideration of characteristics of the major field and university realities. 10 program outcomes were mapped with all courses in the program. 5 probe courses were selected and their course learning objectives were defined. Measurements of the course learning objective were made by term project and written course test. With using course-embedded assesment, the measurement system of the program outcomes should be changed.

• ETRI Journal
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• 제41권2호
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• pp.160-166
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• 2019

A novel analytical method based on the cavity mode theory to design a metasurface (MS) is proposed in this study. We carefully analyzed the phase and amplitude characteristics of the incident wave and transmitted wave, and successfully designed a circular polarization conversion MS by introducing a cutting structure with wider operation bandwidth and higher radiation direction gain compared with that of the original MS. For the measurements, a microstrip antenna operating at 2.4 GHz was used as the source antenna to verify the designed MS. The simulation and measurement results agree well with each other.

• 전기의세계
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• 제14권1호
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• pp.5-12
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• 1965

In the designs of the sensitive electronic devices such as phase sensitive detector, X-ray diffractometer, and neutron diffractometers, we must take into account the geometrical factors in a coil systems and extraneous stray fields. Input wave forms in such a sensitive electronic devices are often altered by the influence of these factors. Since the magnitude of the stray fields is generally very small, this affection may be removed by applying a good shielding but it is not ease to remove the affection from a geometrical factor. This affection must be however calculated by the theoretical methods and analytical solution in the equation of these factors. The fundamental purpose of this paper lie in the theoretical calculations and practical measurements of the geometrical factor in the coil systems, finite solenoid, and four point prove. In the heoretical calculations, the geometrical factors in the coil systems were calculated by applying the elliptic functions and in the contact points were calculated by applying the elliptic functions and in the contact points were calculated by applying the eigen functions and the infinite series. The measurements were carried out by using the sensitive electronic device made from author's design, as shown in the Fig. 9. The result of this work has verified the essential correctness of theoretical investigations and measuring techniques of geometrical factors on the design of sensitive electronic devices. It also has several advantages such that: (1) all the data obtained may give effective data to designer to work on the field of sensitive electronic devices or microelectronic devices, (2) it has evidently explained the characteristics of electrical investigations and physical definition, and has removed the conventional error of geometrical factors in the coil systems and contact points.

• 한국산학기술학회논문지
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• 제13권6호
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• pp.2428-2434
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• 2012

본 논문은 제동 시스템에서 전자식 주행안정 제어장치(ESC)의 유압 모듈레이터의 솔레노이드 밸브 제어에 대한 것이다. ESC의 전자제어유니트(ECU)를 제어하기 위한 방법으로 고주파수 제어와 슬로프 제어를 적용하였으며, 서지 압력 및 전자파간섭(EMI) 저감 특성을 연구하였다. 고주파수에서의 전자파 방출을 줄이기 위하여 ECU 출력 단에 슬로프 제어 기능을 추가하였다. 측정결과 제동 시스템에서 고주파수 ECU의 솔레노이드 밸브제어 방법에 따라 서지 압력과 전자파 방출이 저감될 수 있음을 확인하였다. 결론적으로 고주파수 ECU 제어 연구 결과에 의해 제동 시스템 성능을 향상방안을 제시하고자 한다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.43-46
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• 2003

This paper presents capacity characteristics of the indoor LOS(Line-Of-Sight) propagation channel for MIMO system at 5GHz. The distance between antenna elements, their moving path, and number of transmitting and receiving antennas can be determined by wanted eigen-vlaue, and channel capacity of the MIMO communication channel using only reliable simulation without measurements. The simulation uses 3D Ray tracing and patch scattering model to which electromagnetic material constants are applied. As distance between antenna elements increases, distribution of the eigen-value show a tendency to decrease, but channel capacity increases in LOS environment. However, despite of short distance between antenna elements, large value of channel capacity is obtained in positions which have high AS. When the position of receiver antennas are shifted, channel capacity hardly changed, and as number of antenna elements increases, channel capacity also increases regularly.

• 한국전기전자재료학회논문지
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• 제31권6호
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• pp.367-371
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• 2018

1,200 V class junction barrier schottky (JBS) diodes and schottky barrier diodes (SBD) were simultaneously fabricated on the same 4H-SiC wafer. The resulting diodes were characterized at temperatures from room temperature to 473 K and subsequently compared in terms of their respective I-V characteristics. The parameters deduced from the observed I-V measurements, including ideality factor and series resistance, indicate that, as the temperature increases, the threshold voltage decreases whereas the ideality factor and barrier height increase. As JBS diodes have both Schottky and PN junction structures, the proper depletion layer thickness, $R_{on}$, and electron mobility values must be determined in order to produce diodes with an effective barrier height. The comparison results showed that the JBS diodes exhibit a larger effective barrier height compared to the SBDs.

• Interaction and multiscale mechanics
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• 제1권2호
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• pp.177-190
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• 2008

In this paper, both experimental measurement and theoretical analysis are used to investigate the out-of-plane resonant characteristics of a cantilevered piezoceramic plate in air and three different kinds of fluid. The experimental method, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI), is the major technique used in this study to measure the resonant characteristics of the cantilivered piezoceramic plate. Both resonant frequencies and full-field mode shapes are obtained from this experimental technique. Numerical computations based on the finite element analysis are presented for comparison with the experimental results. Good quality of mode shapes for the cantilevered piezoceramic plate in air is obtained from the AF-ESPI technique. However, the quality decreases as the viscosity of fluids increases. From the results provided from experimental measurements and numerical computations, it is indicated that the resonant frequencies of the cantilevered piezoceramic plate in fluid decrease with the increase of the viscosity of fluids. Good agreements between the experimental measured data and the numerical calculated results are found for both resonant frequencies and mode shapes of the cantilevered piezoceramic plate in fluid.

• E2M - 전기 전자와 첨단 소재
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• 제7권6호
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• pp.473-480
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• 1994

The electron tunnel effect in polvimide LB films sandwiched between metal electrodes has been investigated in the present work by a study of both the elastic and inelastic tunneling components. By the results of elastic tunneling experiments in Au/Pl/Au tunneling junction, we can judge the height and thickness of tunnel barrier. The inelastic current in Inelastic Electron Tunneling Spectroscopy(IETS) is due to the interaction of the tunneling electron with the vibrational modes of the molecular species in the barrier. Measurements are done on Au/PI/Pb tunneling junctions. The spectra obtained are the second derivatives of the current-voltage characteristics of these junctions : specifically, d$^{2}$1/dV$^{2}$ as a function of voltage V. Because the energies measured by IETS can be directly compared to those measured by infrared and Raman spectroscopy, IR-RAS spectroscopy also measured for reference.

• 한국전기전자재료학회논문지
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• 제30권3호
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• pp.180-184
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• 2017

In this study, we examine the electrical properties of diketopyrrolopyrrole (DPP) containing polymer semiconductors that have been reported to show high performance with ambipolar characteristics. We prepared three different DPP based polymer semiconductors (PDPPTPT, PDPP3T, and PDPP2T-TT) and fabricated organic thin film transistors (OTFTs) with ambipolar polymer semiconductors as an active layer. All three DPP polymers showed only p-type properties at initial measurements. However, after annealing in vacuum oven for 24 hours, it was found that the DPP based polymers have both p-type and n-type properties. It is speculated that the residual impurities supposedly regarded as a strong electron trap source were eliminated during the vacuum process.